On Thu, 20 Oct 2022 09:00:05 +0000
Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
> A linker script has a few benefits:
> - We can easily define a lowcore and load the snippet from 0x0 instead
> of 0x4000 which makes asm snippets behave like c snippets
> - We can easily define an invalid PGM new PSW to ensure an exit on a
> guest PGM
> - We can remove a lot of the offset variables from lib/s390x/snippet.h
>
> As we gain another step and file extension by linking, a comment
> explains which file extensions are generated and why.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
> lib/s390x/snippet.h | 14 +++++---------
> s390x/Makefile | 18 ++++++++++++++----
> s390x/mvpg-sie.c | 2 +-
> s390x/pv-diags.c | 6 +++---
> s390x/snippets/asm/flat.lds | 35 +++++++++++++++++++++++++++++++++++
> 5 files changed, 58 insertions(+), 17 deletions(-)
> create mode 100644 s390x/snippets/asm/flat.lds
>
> diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet.h
> index b17b2a4c..fcd04081 100644
> --- a/lib/s390x/snippet.h
> +++ b/lib/s390x/snippet.h
> @@ -32,8 +32,6 @@
>
> #define SNIPPET_PV_TWEAK0 0x42UL
> #define SNIPPET_PV_TWEAK1 0UL
> -#define SNIPPET_OFF_C 0
> -#define SNIPPET_OFF_ASM 0x4000
>
>
> /*
> @@ -57,15 +55,14 @@ static const struct psw snippet_psw = {
> * @vm: VM that this function will populated, has to be initialized already
> * @gbin: Snippet gbin data pointer
> * @gbin_len: Length of the gbin data
> - * @off: Offset from guest absolute 0x0 where snippet is copied to
> */
> static inline void snippet_init(struct vm *vm, const char *gbin,
> - uint64_t gbin_len, uint64_t off)
> + uint64_t gbin_len)
> {
> uint64_t mso = vm->sblk->mso;
>
> /* Copy test image to guest memory */
> - memcpy((void *)mso + off, gbin, gbin_len);
> + memcpy((void *)mso, gbin, gbin_len);
>
> /* Setup guest PSW */
> vm->sblk->gpsw = snippet_psw;
> @@ -87,23 +84,22 @@ static inline void snippet_init(struct vm *vm, const char *gbin,
> * @hdr: Snippet SE header data pointer
> * @gbin_len: Length of the gbin data
> * @hdr_len: Length of the hdr data
> - * @off: Offset from guest absolute 0x0 where snippet is copied to
> */
> static inline void snippet_pv_init(struct vm *vm, const char *gbin,
> const char *hdr, uint64_t gbin_len,
> - uint64_t hdr_len, uint64_t off)
> + uint64_t hdr_len)
> {
> uint64_t tweak[2] = {SNIPPET_PV_TWEAK0, SNIPPET_PV_TWEAK1};
> uint64_t mso = vm->sblk->mso;
> int i;
>
> - snippet_init(vm, gbin, gbin_len, off);
> + snippet_init(vm, gbin, gbin_len);
>
> uv_create_guest(vm);
> uv_set_se_hdr(vm->uv.vm_handle, (void *)hdr, hdr_len);
>
> /* Unpack works on guest addresses so we only need off */
> - uv_unpack(vm, off, gbin_len, tweak[0]);
> + uv_unpack(vm, 0, gbin_len, tweak[0]);
> uv_verify_load(vm);
>
> /*
> diff --git a/s390x/Makefile b/s390x/Makefile
> index 3b175015..0eaa72f4 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -124,6 +124,13 @@ else
> snippet-hdr-obj =
> endif
>
> +# Each snippet will generate the following files (in order): \
> + *.o is a snippet that has been compiled \
> + *.ol is a snippet that has been linked \
> + *.gbin is a snippet that has been converted to binary \
> + *.gobj is the final format after converting the binary into a elf file again, \
> + it will be linked into the tests
> +
> # the asm/c snippets %.o have additional generated files as dependencies
> $(SNIPPET_DIR)/asm/%.o: $(SNIPPET_DIR)/asm/%.S $(asm-offsets)
> $(CC) $(CFLAGS) -c -nostdlib -o $@ $<
> @@ -131,17 +138,20 @@ $(SNIPPET_DIR)/asm/%.o: $(SNIPPET_DIR)/asm/%.S $(asm-offsets)
> $(SNIPPET_DIR)/c/%.o: $(SNIPPET_DIR)/c/%.c $(asm-offsets)
> $(CC) $(CFLAGS) -c -nostdlib -o $@ $<
>
> -$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.o
> - $(OBJCOPY) -O binary -j ".rodata" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $(patsubst %.gbin,%.o,$@) $@
> +$(SNIPPET_DIR)/asm/%.ol: $(SNIPPET_DIR)/asm/%.o
> + $(CC) $(LDFLAGS) -o $@ -T $(SNIPPET_DIR)/asm/flat.lds $<
> +
> +$(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.ol
> + $(OBJCOPY) -O binary -j ".rodata" -j ".lowcore" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $< $@
> truncate -s '%4096' $@
can't you do $(CC) and $(OBJCOPY) in one step like you do for C
snippets? then you don't need the .ol intermediate
>
> $(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS)
> - $(CC) $(LDFLAGS) -o $@ -T $(SRCDIR)/s390x/snippets/c/flat.lds $< $(snippet_lib) $(FLATLIBS)
> + $(CC) $(LDFLAGS) -o $@ -T $(SNIPPET_DIR)/c/flat.lds $< $(snippet_lib) $(FLATLIBS)
> $(OBJCOPY) -O binary -j ".rodata" -j ".lowcore" -j ".text" -j ".data" -j ".bss" --set-section-flags .bss=alloc,load,contents $@ $@
> truncate -s '%4096' $@
>
> $(SNIPPET_DIR)/asm/%.hdr: $(SNIPPET_DIR)/asm/%.gbin $(HOST_KEY_DOCUMENT)
> - $(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x4000,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
> + $(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
>
> $(SNIPPET_DIR)/c/%.hdr: $(SNIPPET_DIR)/c/%.gbin $(HOST_KEY_DOCUMENT)
> $(GEN_SE_HEADER) -k $(HOST_KEY_DOCUMENT) -c $<,0x0,0x00000000000000420000000000000000 --psw-addr 0x4000 -o $@
> diff --git a/s390x/mvpg-sie.c b/s390x/mvpg-sie.c
> index 46a2edb6..17e209ad 100644
> --- a/s390x/mvpg-sie.c
> +++ b/s390x/mvpg-sie.c
> @@ -87,7 +87,7 @@ static void setup_guest(void)
>
> snippet_setup_guest(&vm, false);
> snippet_init(&vm, SNIPPET_NAME_START(c, mvpg_snippet),
> - SNIPPET_LEN(c, mvpg_snippet), SNIPPET_OFF_C);
> + SNIPPET_LEN(c, mvpg_snippet));
>
> /* Enable MVPG interpretation as we want to test KVM and not ourselves */
> vm.sblk->eca = ECA_MVPGI;
> diff --git a/s390x/pv-diags.c b/s390x/pv-diags.c
> index 9ced68c7..d472c994 100644
> --- a/s390x/pv-diags.c
> +++ b/s390x/pv-diags.c
> @@ -28,7 +28,7 @@ static void test_diag_500(void)
>
> snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_500),
> SNIPPET_HDR_START(asm, snippet_pv_diag_500),
> - size_gbin, size_hdr, SNIPPET_OFF_ASM);
> + size_gbin, size_hdr);
>
> sie(&vm);
> report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
> @@ -83,7 +83,7 @@ static void test_diag_288(void)
>
> snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_288),
> SNIPPET_HDR_START(asm, snippet_pv_diag_288),
> - size_gbin, size_hdr, SNIPPET_OFF_ASM);
> + size_gbin, size_hdr);
>
> sie(&vm);
> report(vm.sblk->icptcode == ICPT_PV_INSTR && vm.sblk->ipa == 0x8302 &&
> @@ -124,7 +124,7 @@ static void test_diag_yield(void)
>
> snippet_pv_init(&vm, SNIPPET_NAME_START(asm, snippet_pv_diag_yield),
> SNIPPET_HDR_START(asm, snippet_pv_diag_yield),
> - size_gbin, size_hdr, SNIPPET_OFF_ASM);
> + size_gbin, size_hdr);
>
> /* 0x44 */
> report_prefix_push("0x44");
> diff --git a/s390x/snippets/asm/flat.lds b/s390x/snippets/asm/flat.lds
> new file mode 100644
> index 00000000..388d7d5d
> --- /dev/null
> +++ b/s390x/snippets/asm/flat.lds
> @@ -0,0 +1,35 @@
> +SECTIONS
> +{
> + .lowcore : {
> + /* Restart new PSW for booting via PSW restart. */
> + . = 0x1a0;
> + QUAD(0x0000000180000000)
> + QUAD(0x0000000000004000)
> + /*
> + * Invalid PGM new PSW so we hopefully get a code 8
> + * intercept on a PGM for PV snippets.
> + */
> + . = 0x1d0;
> + QUAD(0x0008000000000000)
> + QUAD(0x0000000000000001)
> + }
> + . = 0x4000;
> + .text : {
> + *(.text)
> + *(.text.*)
> + }
> + . = ALIGN(64K);
> + etext = .;
> + . = ALIGN(16);
> + .data : {
> + *(.data)
> + *(.data.rel*)
> + }
> + . = ALIGN(16);
> + .rodata : { *(.rodata) *(.rodata.*) }
> + . = ALIGN(16);
do you really need to ALIGN(16) right after ALIGN(64K) ?
> + __bss_start = .;
> + .bss : { *(.bss) }
> + __bss_end = .;
> + . = ALIGN(64K);
why align the end? and why 64K instead of e.g. 4K?
> +}
